This invention relates to an automatic molten metal supply and injection device used for casting molten metal into a metallic mold or a mold for sand mold casting or for casting semihardened molten metal into a mold.
Automatic molten metal supply devices and injectors for casting molten metal into a mold are available in various types and structures. FIGS. 7 to 9 show conventional automatic molten metal supply devices and injectors of different types.
The automatic molten metal supply device and injector shown in FIGS. 7A-8B includes a molten metal retaining furnace 1 having an outlet 2 to which is connected to the suction side of an electromagnetic pump 3. In the furnace, the level of molten metal is kept constant. An upright injection cylinder 6 is provided under a pair of openable molds 4, 5. Split sleeves 7 and 8 are fixed to the bottom ends of the molds 4 and 5, respectively. The discharge port of the electromagnetic pump 3 is connected to the sleeve 7 of the stationary mold 4.
The molds 4, 5, which are initially open as shown in FIG. 7A, are closed as shown in FIG. 7B, and the electromagnetic pump 3 is activated to supply a required amount of molten metal from the furnace 1 into the now closed sleeves 7, 8. Then, as shown in FIG. 8A, the cylinder 6 is extended to supply molten metal from the sleeves 7, 8 into a cavity of the molds 4, 5 under pressure.
The cylinder 6 is then retracted as shown in FIG. 8B, and the molds 4 and 5 are opened,to remove the molded product.
The automatic molten metal supply device and injector shown in FIGS. 9A-9C includes a pair of openable molds 11 and 12. A horizontal sleeve 14 communicating with the cavity 13 is fixed to one of the molds 11 and 12. The sleeve 14 has a molten metal supply port at one end thereof. An injection plunger 16 is inserted in the sleeve 14.
With this automatic molten metal supply device and injector, with the molds 11, 12 closed, molten metal in the container 17 is poured through a molten metal supply port 15 into the sleeve 14 and supplied into the cavity 13 of the molds 11, 12 under the pressure by the plunger 16. The plunger 16 is then retracted, and the molds 11, 12 are opened to remove the product.
These devices have a problem in that while molten metal is being supplied into the sleeve, an air layer tends to appear in the cavity, so that air tends to mix into the molten metal. This increases the possibility of pores being developed in the end product. Also, if a magnesium alloy is cast, air mixed into the molten magnesium alloy can cause explosion.
Also, in these conventional devices, molten metal can be supplied only after the molds have been closed. Working efficiency is thus low.
An object of this invention is to provide an integrated automatic molten metal supply and injection device which can prevent mixing of air into molten metal being supplied, which can reduce the possibility of explosion and the development of pores, and which makes it possible to supply molten metal irrespective of whether the molds are open or closed.